body {
  margin: 0;
  padding: 0;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

.container {
  width: 300px;
  height: 300px;
  /* background-color: transparent; */
  background-color: #74b9ff;
  border-radius: 10px;
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
}

.container::before {
  content: "";
  position: absolute;
  top: -10px;
  left: -10px;
  width: 20px;
  height: 20px;
  background: linear-gradient(
    135deg,
    rgba(0, 119, 182, 0.2) 0%,
    rgba(0, 150, 199, 0.1) 100%
  );
  border-radius: 10px;
  box-shadow: 0 0 15px rgba(0, 119, 182, 0.5), 0 0 30px rgba(0, 150, 199, 0.3),
    inset 0 0 10px rgba(0, 119, 182, 0.2);
  animation: flow 3s linear infinite;
  z-index: -1;
}

@keyframes flow {
  0% {
    width: 20px;
    height: 20px;
  }
  20% {
    left: -10px;
    top: -10px;
    width: calc(100% + 20px);
    height: 20px;
  }
  40% {
    left: calc(100% - 10px);
    top: -10px;
    width: 20px;
    height: calc(100% + 20px);
  }
  60% {
    top: calc(100% - 10px);
    left: -10px;
    width: calc(100% + 20px);
    height: 20px;
  }
  80% {
    top: -10px;
    left: -10px;
    width: 20px;
    height: calc(100% + 20px);
  }
  100% {
    top: -10px;
    left: -10px;
    width: 20px;
    height: 20px;
  }
}
